Researchers are urging formulators to remove two dyes from skin care products and after-shave as they pose a health risk to consumers.

Brilliant Blue (E133) and Patent Blue (E131), both authorized as cosmetic colouring substances in the EU, have been found to permeate shaved or damaged skin in a recently published study in the journal Food and Chemical Toxicology by Jarmila Hojerová and her team.

“Currently, there is evidence of health risks of triphenylmethane dyes after systemic absorption. Both dyes showed no measurable permeation through intact skin but significant permeation was found through shaven skin,” says Hojerová.

Method

The study investigated the fate of BB and PB after 24-h in vitro diffusion, firstly through intact and secondly through shaven pig-ear skin from four leave-on cosmetics under in-use conditions.

From 250 ng/cm2 of dye in one applied dose there were found 52 ng/cm2 of BB and 91 ng/cm2 of PB from ethanol-based after-shave, 39 ng/cm2 of BB and 86 ng/cm2 of PB from ethanol-free facial-cleanser, 35 ng/cm2 of BB and 43 ng/cm2 of PB from O/W emulsion, and no amount from W/O emulsion, as available to become systemically absorbed.

“Findings are troubling, particularly with regard to the frequent use of after-shave products by the male population,” notes Hojerová.

Regulation

The triphenylmethane dyes have a wide range of applications in industries and consumer products either alone or in combination with other dyes, to produce various shades of blue, green, and violet.

In the European Union, BB is authorized as a cosmetic colouring substance Acid Blue 9 without a quantitative limit. It is also approved by the Food and Drug Administration (FDA) in the US as an additivefor usage in food, drug, and cosmetic products.

Unlike BB, there is no consistency in the regulatory framework for the use of PB. In the EU, PB is authorized as a cosmetic colouring substance Acid Blue 3 without a quantitative limit; however, in some countries, it is not allowed in cosmetic products.

Warning

“The exposure to Brilliant Blue FCF and Patent Blue V poses only minimal risk for systemic absorption when applying for the first time to the human intact skin in leave-on cosmetic products similar to the model vehicles,” explains Hojerová.

The study also suggests that the normal process of shaving significantly increases the potential of systemic availability of both dyes from hydrophilic vehicles; which is worrying when taking into account the frequency of skin treatment after shaving and depilation with cosmetic products containing the dyes, perhaps during the long years of life.

“Taken together, the results suggest that due to possible adverse health effects of BB and PB for the people, both dyes should not be used in topical products, which are primarily intended for slightly damaged skin,” adds the research.

Unnecessarily alarming

Despite the research presented by the Slovak scientists, the International Association of Color Manufacturers has questioned the validity of the claims made.

The IACM has branded the study "misleading" and "unnecessarily alarming," as the colourings in question have been approved for use in the US over 90 years.

Despite being more concerned with implications of the dyes used in edible products, the IACM has reiterated the safety of BB, and says that “the colour industry takes its responsibility for consumer safety seriously.”

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